Band electrode submerged arc welding of chromium stainless steel and a material used in said welding

ABSTRACT

THE BAND ELECTRODE SUBMERGED ARC-WELDING OF CHROMIUM STAINLESS STEEL, A WELD METAL WHICH IS EXCELLENT IN DUCTILITY AND CRACK RESISTANCE CAN BE OBTAINED BY MEANS OF USING A BAND ELECTRODE OF CHROMIUM STAINLESS STEEL IN COMBINATION WITH A FLUX CONTAINING 25 TO 50 PERCENT CALCIUM CARBONATE, 30 TO 50 PERCENT ALUMINA, 1 TO 10 PERCENT FLUORITE, AND 1 TO 10 PERCENT MAGNESIA, SAID ELECTRODE AND/OR FLUX BEING BLENDED WITH ALUMINUM, TITANIUM, COLUMBIUM, NITROGEN, CHROMIUM, MANGANESE, AND NICKEL OR COBALT, SO THAT THE WELD METAL CONTAINS THESE ELEMENTS IN THE RATIO OF 0.015 TO 0.15 PERCENT ALUMINUM, 0.0025 TO 0.22 PERCENT TITANIUM, 0.35 TO 2,8 PERCENT COLUMBIUM, 0.01 TO 0.075 PERCENT NITROGEN, 8.5 TO 25 PERCENT CHROMIUM, 0.15 TO 2.0 PERCENT MANGANESE, AND LESS THAN 2.8 PERCENT NICKEL OR COBALT.

United States Patent Inventors Tomokazu Godai;

Makoto Tomita; Osamu Tanaka, Kamakura-shi, Japan AppLNo. 788,240 Filed Dec.3l, 1968 Patented Mar. 23, 1971 Assignee Kobe Steel, Ltd.

Kobe, Japan Priority Jan. 9, 1968 Japan 43/966 BAND ELECTRODE SUBMERGED ARC WELDING OF CHROMIUM STAINLESS STEEL AND A MATERIAL USED IN SAID WELDING References Cited UNITED STATES PATENTS 3,320,100 5/1967 Coless Primary Examiner-J. V. Truhe Assistant Examiner-Lawrence A. Rouse Att0rney--Wenderoth, Lind and Ponack blended with aluminum, titanium, columbium, nitr0gen,.

chromium, manganese, and nickel or cobalt, so that the weld metal contains these elements in the ratio of 0.015 to 0.15 percent aluminum, 0.0025 to 0.22 percent titanium, 0.35 to 2,8 percent columbium, 0.01 to 0.075 percent nitrogen, 8.5 to 25 percent chromium, 0.15 to 2.0 percent manganese, and less than 2.8 percent nickel or cobalt.

EAND ELECTRODE SUBMERGED ARC WELDWG OF (IMOMHUM STAHNLEES STEEL AND A MATERIAL UED IN SAID WELDHNG BACKGROUND OF THE INVENTION it is publicly known from Japanese Pat. No. 496,51 1 that in the welding of high-chromium stainless steel, aluminum, titanium or columbium can be contained to prevent the lowering of ductility and impact value of welded metal. And also, as shown in Japanese Pat. No. 466,586, the composition having the ingredients in the following range has well been known as a flux for submerged arc-welding of high-chromium stainless steel:

Wollastonite 10-30 percent Fluorite 10-20 percent Calcium carbonate 20-40 percent Potash feldspar 3-15 percent Cryolite l- 10 percent Aluminum fluoride 10-30 percent Ferromanganese ll percent lFerrocolumbium ll 0 percent Ferroaluminum lpercent Ferrotitanium 1-10 percent Metallic Titanium 1-5 percent In general, in the submerged arc-welding using band electrode of 0.2 to 0.8 mm. in thickness and to 100 mm. in width, a smooth bead of 20 to 100 mm. in width and less penetration can be efficiently obtained in the course of one pass. However, in the submerged arc-welding of high-chromium stainless steel with the use of the band electrode, even if the conventional flux for submerged arc-welding is employed, the practically usable good bead and mechanical properties could not be obtained. That is, in case of the conventional flux containing silicon oxide, the silicon oxide was reduced due to a strong deoxidizing action of aluminum, titanium and columbium, and the weld metal was made to contain a great amount of silicon, and ductility of the weld metal was almost lost, even though the bead shape as well as workability was satisfactory, thus being far from practical use. Also, in case of a blending in that the flux to be used contains little silicon oxide, an un-' dercut occurred at the bead ends, the bead rough face was uneven, and detachability of slag being inferior, it was difficult to obtain a satisfactory bead.

The inventors of this invention, after a series of experimental studies, have been able to practicalize the highly basic flux for submerged arc-welding free from the above-indicated defects, and have finally come to succeed in the development of a material for band electrode submerged arc-welding, which is excellent in workability, and is capable of obtaining a welded portion excelled in ductility and crack resisting property by combining the flux and the band electrode being the specific ingredient.

SUMMARY OF THE INVENTION The present invention is concerned with a submerged arcwelding of chromium stainless steel and a material used in said welding.

That is to say, the band electrode submerged arc-welding of chromium stainless steel in the process of the present invention is characterized by using a band electrode of chromium stainless steel in combination with the flux containing -50 percent calcium carbonate, -50 percent alumina, 1-10 percent fluorite, and l-l0 percent magnesia, said electrode and/or flux being blended with aluminum, titanium, columbium, nitrogen, chromium, manganese, and nickel or cobalt, so that the weld metal contains these elements in the ratio of 0.0l5-0.l5 percent aluminum, 0.025-0.22 percent titanium, 0.352.8 percent columbium, 0.01-0.075 percent nitrogen, 85-25 percent chromium, 0.152.0 percent manganese, and less than 2.8 percent nickel or cobalt.

Furthermore, a welding material to be used the process of this invention is characterized by the combination of a band electrode of chromium stainless steel and a flux containing 25- 50 percent calcium carbonate, 30-50 percent alumina, 1- -l0 percent fluorite and l- 10 percent magnesia, in that said electrode and/or flux being blended with alloy elements such as aluminum, titanium, columbium, nitrogen, chromium manganese, nickel or cobalt in the following ratio:

a. when the alloy elements are blended in the flux:

aluminum 0.5-5 percent titanium l-S'percent columbium 1-7 percent nitrogen 0.025-0.25 percent chromium not more than 30 percent manganese l7 percent nickel or cobalt 0.5-5 percent b. when above-indicated alloy elements are blended in the band electrode:

aluminum 0.3-4 percent titanium 0.5-4 percent columbium 0.5-4 percent nitrogen 0.02-0. 15 percent chromium 11-30 percent manganese 0.4-5 percent nickel or cobalt 0.2-3.5 percent 0. when above-indicated alloy elements are blended into both the flux and band electrode:

aluminum 0-5 percent titanium 0-5 percent columbium 0-7 percent nitrogen 0-0.25 percent chromium 0-30 percent manganese O-7 percent nickel or cobalt 0-5 percent in the flux, and adding aluminum O-3 percent titanium 0-4 percent columbium 0-4 percent nitrogen 0-0.l5 percent chromium 0-30 percent manganese 0-5 percent nickel or cobalt 0-3.5 percent in the band electrode.

It should be noted, however, that (c) is not limited to the case in that all of the above-indicated alloy elements are blended separately in the flux and in the electrode respectively, but on the contrary, some of those elements can be blended in only either one of the two. Similarly, the blending combination in case of blending them separately in the two can be carried out on an optional basis within the required range of the blending ratio. Nevertheless, it goes without saying that said blending combination should be conducted so as not to deviate from the above-indicated alloy element component range in the weld metals.

Incidentally, columbium is difficult to be separated from tantalum belonging to the same group as the former, and because it always is accompanied by tantalum, columbium referred to in the specification of this application will be considered to contain a certain amount of tantalum (that is, columbium tantalum).

DETAILED EXPLANATION OF THE PREFERRED EMBODIMENT Hereinbelow is the explanation in detail as to the reason why the welding method and the material thereof in a process of the present invention is specified as in the foregoing.

The flux in the present invention is characterized by being a flux having strong basicity with calcium carbonate and alumina as the basis thereof. Calcium carbonate acts effectively in intercepting arc from the atmosphere by means of reducing atmosphere of carbon dioxide gas generated by thermal decomposition, and at the same time, calcium oxide which is a decomposed product thereof contributes to form a strong basic slag along with said alumina. At such time, when the blending amount of calcium carbonate is less than 25 percent,

the fluidity of slag is deteriorated, and when it is more than 50 percent, there is much generation of gas, and results in the worsening of bead appearance. Therefore, the blending ratio should be limited to the range of 2550 percent.

Further, alumina acts effectively to maintain the melting point of slag-low by the blending of more than 25 percent. It should be noted, however, that a great amount of blending will raise the fluidity of slag on the contrary, thus resulting in instability of arc, and consequently; the blending should be not more than 50 percent.

In addition to the basic flux components, l-l percent fluorite, and ll0 percent magnesia are blended, because by blending-in of fluorite in the amount greater than 1 percent, it is capable of making the weld penetration thin, and eliminating the overlapping about the ends of bead. Also because a blending of more than percent will cause such occurrences as undercut or the like, the maximum blending percentage should be the said value. In the meantime, even though magnesia contributes to the stabilization of arc and improvement in the detachability of slag, even the blending of less than 1 percent cannot bring about the intended effect, while the blending of more than 10 percent will thicken the weld penetration, resulting in frequent occurrence of slag baking, which is not suitable to the buildup welding portion. In order to expect the best possible result, therefore, the blending ratio is limited to the range as explained above.

In the following an explanation is given specifically as to the object of adding such alloy elements as aluminum, titanium, columbium, nitrogen, chromium, manganese and nickel or cobalt to the weld metals in the process of the present invention. In the first place, the addition of aluminum, titanium and columbium is effected in an aim to expect the function as deoxidizing agents, and at the same time, by the addition of these components into the weld metals, to finely divide the crystalline particles, and to improve the ductility and crack resisting property thereof. And in the band electrode submerged arc-welding, input becomes large due to employment of electric current of 300 A. l ,600 A., the shield of arc atmosphere due to gas generated from welding is nearly complete, and the amount of nitrogen from air is smaller compared with the case of manual welding. Because of this, aluminum, titanium and columbium alone would not be sufficient to carry out the finely dividing of the crystalline particles. Furthermore, in order to finely divide the crystalline particles, it is imperative to forcedly produce nitrides from aluminum, titanium, columbium and nitrogen by adding nitrogen to the weld metals. In the meantime, the addition of nickel or cobalt and manganese will contribute to the increase of ductility about the part to be welded, and is carried out with the aim of improving the crack resisting property. On the other hand, an optional amount of chromium in the weld metal suitable to the purpose may be added in order to obtain the desired value depending on the use. In order to add the alloy elements into the weld metal as explained in the foregoing, and to accomplish the purpose of object above, it is necessary to establish the ratio of addition of above-indicated respective alloy elements into the weld metal due to the following reasons.

That is to say, aluminum and titanium are not capable of exhibiting the intended effect when the respective percentage is less than the above-indicated range due to oxidation wear. And when the percentage is above the upper limit, aluminum and titanium amount in the weld metal becomes excessively large, resulting in lowering the ductility. On the other hand, the addition of columbium is aimed at solidifying carbon in the weld metal as columbium carbide, and to prevent martensite from separation. However, the blending amount below the lower limit does not exhibit the intended effect sufficiently, and similarly when it is above the upper limit, the metal will be made brittle. Therefore, such blending above or below the limit must be avoided. Nickel or cobalt and manganese exhibit the above-mentioned effect by blending above the upper limit. However, when these elements are added in a great amount, the former will be a cause of hardening at the time of afterheat treatment, while the latter will also harden the weld metal, and therefore, no blending above the upper limit is preferable. Nitrogen also exhibits the above-shown effect in case of blending above the lower limit, but when blended above the upper limit, the amount of gas to be generated will be great, which will be a cause of defects on the bead face, and therefore, such blending above the upper limit is not preferable.

In the meantime, chromium will be blended in an optional amount, and the blending ratio will be established taking into consideration the amount of high-chromium stainless steel put to practical use at present. In order to carry out the addition of above-indicated respective alloy elements into the weld metal so as to maintain the range of composition as shown in the foregoing paragraphs, the intended object can be sufficiently accomplished by (a) blending said respective alloy elements into only the flux, or (b) into only the band electrode, or (c) by blending one or more of the alloy elements into both the flux and the band electrode. And also in this respect, after a series of experimental researches, the inventors of this invention have come to practicalize the welding material by establishing the most appropriate blending ratio for each one of the above-indicated cases of (a), (b) and (c).

Incidentally, above-shown blending ratio has been established on the basis of providing the respective alloy elements from the flux and/or the band electrode into the weld metal. And thus, the amount of yield has been obtained as a result of respective experimental researches conducted by the inventors et al. of this invention. Thetable in the following shows the amount of yield.

A. Yield obtained when provided from the flux aluminum about 3 percent titanium 2-5 percent columbium 35--40 percent chromium about percent manganese 15-30 percent nickel or cobalt 30-55 percent B. Yield obtained from the band electrode aluminum about 5 percent titanium about 5 percent columbium about 70 percent nitrogen about 50 percent chromium about 75 percent manganese about 40 percent nickel or cobalt about 80 percent (The yield referred to in the above is a value determined by consideration of the welding ratio with the base metal, and also of the consumption ratio or the band electrode and flux.) Incidentally, in case of blending calcium, titanium, columbium or the like into the flux, it will be effective to blend a amount corresponding to the above-indicated blending ratio as shown in the following in the form of iron alloy. And further, it is possible to blend nitrogen in the form of metal compound or others containing nitrogen.

ferroaluminum (50 percent Al) ferrotitanium (45 percent Ti) ferrocolumbium (70 percent Cb) l.4l0 percent chromium nitride (5 percent N) 0.5-5 percent The following will show the working embodiments of the present invention.

1-10 percent 2.2-ll percent EXAMPLE 1 (When alloy elements are added only to the flux 1. Welding material a. flux to be used calcium carbonate 31 percent alumina 31 percent fluorite 2.5 percent magnesia 56 percent ferroaluminum (50 percent A1) 3 percent ferrotitanium (45 percent Ti) 3 percent ferrocolumbium (70 percent Cb) 5.5 percent chromium nitride (5 percent N) 2.5 percent 6 metallic nickel 2 percent and crack resisting property were also excellent. metallic manganese 3 percent metallic chromium 3.5 percent EXAMPLE 3 When water glass was added to these raw materials, which were mixed well, and were sintered to be granulated at a tem- 5 per-attire f 450 C," (When alloy elements are partly added to the band elecb. band electrode to be used trode, and p y to the flux) 4 5() 1. Material to be used Cr 16.4 percent a. flux to be used Mn 0.5 percent calcium carbonate 35 percent Si 0.5 percent alumina 31 percent C 0.06 percent fluorite 3.5 percent Ni 0.1 percent magnesia 4.5 percent N 0.02 percent ferroaluminum (50 percent All) 3 percent Fe Balance ferrotitanium (45 percent Ti) 3 percent c. base metal to be used metallic chromium percent C 0.18 percent Water glass was added to these raw materials, which were Si 0. 1 percent mixed well, and were sintered at a temperature of 450 C. Mn 0.5 percent b. band electrode to be used (0.4X50 mm.) Fe Balance 20 Cr 13.5 percent 2. Welding conditions for use Cb 1 .5 percent As a result of carrying out the band electrode submerged N pe n arc-welding on a soft steel plate under above given conditions, Ni 1.2 percent it was found out that a smooth bead of superior quality having Mn 2.0 percent less welding thickness of about 50 mm. was obtained, and the Si 0.5 percent slag detached itself. In the meantime, there was no such de- C 0.05 percent fects as undercut observed at all about the bead ends. Also, as Fe Balance shown in FIG. 2, ductility about the welding portion was suffia material t be used cient, and there was no such defects as cracking. In the follow- Same as in examples 1 and 2 ing are given the data resulting from the chemical components 2- Welding C nditions of the weld metal comparing the case of using the above-men- 850 'AC DC Adverse Polarity) 28 v.Xl7 cm./min. tioned welding material with the case of using the already ex- Superior weld metals as in the previously given examples isting flux. were obtained. Both ductility and crack resisting property Chemical components of metals to be welded (percent) Flux used Cr Si Mn Ni Al Ti Ob N 0 Fe Lateral bend test results conventionally used flux 130 1. 3 0. 5 0. 1 0. 02 O. 12 Balance... Crack occurred at 510 C. Flux in this invention 141 0. 5 1 2 0.7 0.03 0.08 1.0 0.05 0.09 .do 180 0., well bending.

EXAMPLE 2 were excellent.

(When alloy elements are added only to the band electrode) Range of chemical components of the Weld metals aluminum 0015-0. 15 percent Material to be welded titanium 0.0250.22 percent flux to be used columbium 0.352.8 percent calcium carbonate 46 percent mtrogeln Pelee?lt alumina 39 percent chromium 8.525 percent fluorite 4 percent manganese 0. l 5-2.0 percent magnesia 75 percent nickel or cobalt 0. l52.8 percent metallic chromium 35 percent Incidentally, aluminum referred to in the above represents when water glass was added to these raw materials, which soluble aluminum. Soluble aluminum generally referred to in were mixed well, and were sintered at a temperature of 450 analytlcal chemlstl'y Indicates acld'soluble aluminum 1 Q in iron and steel, that is, the one readily soluble in such band electrode to be used (0 4)(5Q mm) mineral acids as hydrochloric acid and sulfuric acid. In terms 163 percent of physicochemistry, it means the aggregate of aluminum in A1 1.1 percent the form of atoms present in magnetite in solid solution, alui 0 percent minum in the state of nitride and aluminum in the state of sul- Cb 5 percent fide. From this reason, A1 0 or the like in steel does not fall N 006 percent under such category. Ni 1.0 percent 2. Yield of alloyelements Mn 2.1 percent a. When the alloy elements are added to the flux C 0.06 percent aluminum about 3 percent Si 0.5 percent titanium 2-5 percent Fe Balance columbium 3540 percent c. Base metal to be used nitrogen 30-40 percent Same as in example 1 chromium about 80 percent 2. Welding conditions manganese 15-30 percent Same as in example 1 nickel or cobalt 30-55 percent Weld metals of superior quality having almost the same b. When the alloy elements are added to the band electrode components as those in example were obtained. Both ductility aluminum about 5 percent titanium about 5 percent columbium about 70 percent nitrogen about 50 percent chromium about 75 percent manganese about 40 percent nickel or cobalt about 80 percent Yield referred to in the above represents welding ratio with the base metal, an also the ratio of consumption of the strip electrode and flux.

EXAMPLE 4 When the alloy elements are partly added to the band electrode, and partly to the flux) l Welding material a. flux to be used calcium carbonate 26 percent alumina 47 percent fluorite 8.3 percent magiesia 1 percent ferroaluminum 8 percent ferrotitanium 5.6 percent ferrocolumbium 2.0 percent metallic nickel 1 percent chromium nitride 0.6 percent Water glass was added to these raw materials, which were mixed well, and were sintered to be granulated at a temperature of about 450 C.

b. band electrode to be used (0.4X50 mm.)

Cr 22 percent Si 0.4 percent Mn 3.8 percent Ni 0.5 percent C 0.05 percent Cb 0.8 percent N 0.12 percent Fe Balance c. base metal to be used C 0.122 percent Si 0.2 percent Mn 0.7 percent M 0.5 percent Fe Balance 2. Welding conditions 800 A. DC, Reverse P0larity)X27 v. l6 cm./min.

The Superior welded portion was obtained as was in the previously given examples. Both ductility and crack resisting property were excellent.

EXAMPLE (When the alloy elements are partly added to the bad electrode, and partly to the flux) 1. Material to be welded a. flux to be used calcium carbonate 29 percent alumina 40 percent fluorite 2 percent magnesia 4 percent ferroaluminum 1.5 percent ferrotitanium 9 percent ferrocolumbium 7.5 percent chromium nitride 1.5 percent metallic nickel 4 percent metallic manganese 1.5 percent Water glass was added to these raw materials, which were mixed well, and were sintered t be granulated at a temperature of about 450 C.

b. band electrode to be used (0.4X50 mm.)

Cr 17.2 percent Si 0.3 percent Mn 0.4 percent Ni 3.0 percent C 0.03 percent N 0.01 percent Al 2.1percent Fe Balance c. base metal to be used Same as in example 4. 2. Welding conditions 850 A. DC, RP)X28 v.X18 cm./min.

A superior welded portion was obtained as in the previously given examples. Both ductility and crack resisting property were also excellent.

EXAMPLE 6 (When the alloy elements are partly added to the band electrode, and partly to the flux) 1. Material to be welded a. flux to be used calcium carbonate 34 percent alumina 43 percent fluorite 7 percent magnesia 4 percent chromium nitride 4 percent metallic manganese 6.5 percent metallic nickel 1.5 percent Water glass was added to these raw materials, which were mixed well, and were sintered to be granulated at a temperature of about 450 C.

b. band electrode to be used (0.4X50 mm.)

Cr 18.5 percent Si 0.3 percent Mn 0.2 percent All 0.5 percent Ti 2.5 percent Cb 3.5 percent C 0.08 percent N 0.01 percent Fe Balance c. base metal to be used C 0.24 percent Si 0.2 percent Mn 0.7 percent Fe Balance 2. Welding conditions 800 A. (DC, RP)X28 n.Xl4 cm./min.

A superior welded portion was obtained as in the previously given examples. Both the ductility and crack resisting property were also excellent.

We claim:

1. A material for band electrode submerged arc-welding of chromium stainless steel comprising a combination of a band electrode of chromium stainless steel and a flux containing essentially 2550 percent calcium carbonate, 3050 percent alumina, ll0 percent fluorite, l--l0 percent magnesia, 0.5- -5 percent aluminum, l5 percent titanium, l-7 percent columbium, 0.025-0.25 percent nitrogen, not more than 30 percent chromium, l-7 percent manganese and 0.5-5 percent nickel or cobalt. 

